libext2fs documentation

No, there currently isnt any documentation on the libext2fs library. The library is relatively
well structured internally, and so most people who have looked
at it haven't had *too* much trouble figuring it out.

It would be nice to have some documentation on it, though, and
I am soliciting volunteers who would be willing to do a first
pass documentation on it; I'm definitely willing to work with
someone who is interested in doing that sort of tech writing.

As for your question, you can absolutely tell it to use a backup
superblock, just take a look at the source code for the
function signature for the ext2fs_open() function. One of the
arguments is "superblock", and that's the block number for
the superblock. You're right that debugfs currently doesn't
have a method for opening the filesystem with a backup
superblock. E2fsck most certainly does have a way to do
this, though, and it's documented in the man page. Try
using "e2fsck -b 8193".